Production of Cyclodextrins from Cornstarch Granules in a Sequential Batch Mode and in the Presence of Ethanol

Abstract

The influence of Toruzyme® cyclomaltodextrin glucanotransferase concentration and the presence of ethanol have been studied for the production of α-, β-, and γ-cyclodextrins (CDs) from 15% (w/v) cornstarch, at 65 °C and pH 6, with the aim of increasing CD yield. The selected concentrations for a single batch reactor were 10% (v/v) ethanol and 0.1% (v/v) enzyme, yielding after 12 h, 37% total CDs, of which 52.2% was α-CD, 38.8% β-CD, and 9.0% γ-CD. The enzyme specific activities per unit mass of protein for producing α-, β-, and γ-CD were 37.25, 19.61, and 8.63 U mg(-1), respectively. Total CD yield per milliliter of enzyme was 55 g. To increase CD yield per enzyme charge and thus reduce costs, the production of CDs was tested with two sequential batches in which a single enzyme charge was used. At the end of the first batch, the enzyme was adsorbed either on 65 °C pretreated starch granules or on raw starch, and a second batch was run with this material. The best result, in this case, was obtained for pretreated starch, increasing total CD produced by 57.4%, with 53.2% α-CD, 36.1% β-CD, and 10.7% γ-CD. CD yield per milliliter of enzyme was then 87 g.

Cassava Bagasse as a Substrate to Produce Cyclodextrins

“…When considering the CM, ethanol was not an efficient reagent, decreasing the CD production (α, β, and γ‐CD) and the conversion rate ( p < 0.05). Ethanol was used to improve the production of CDs, as several studies reported an increase in the production of these components with the use of this reagent . The improvement observed with ethanol addition and CB increases the interest in the use of the CB substrate (now discarded in the cassava starch industries) for CD production.…”

“…Ethanol possible promotes changes in both the hydration and infrastructure of the enzyme (for example, displacement of water molecules by the solvent either on the surface of the protein or in the active site region). The polar groups contained in the solvent may make direct molecular effects on biocatalyst activity …”

“…The concentration of 0.05% (v/v) enzyme and reaction time of 12 h were selected. Calsavara et al and Mimi Sakinah et al also verified that the increase in the enzyme concentration reduced the time to reach the concentration equilibrium of the final product, but significant increase in the CD final concentration was not observed. The pH value was set at 6.0, as previous studies reported higher CD yields at this value, and according to the recommendation of the manufacturer that stated pH 6.0 as the optimum value for the enzymatic reaction …”

“…After the determination of the best CB concentration and temperature, the production of CDs with the addition of 10% ethanol was tested, according to the results obtained by other authors . Ethanol has the function of increasing the conversion efficiency of the substrate and, according to previous studies, 10% of ethanol addition is enough to obtain suitable yields. In addition, for comparison purposes, the production of CDs with CB replacement by cassava dextrin (CM) under the same previous conditions (10% of 10 mM sodium citrate buffer, pH 6.0, the best temperature and substrate concentration) was performed.…”

“…The HPLC analyzes were performed on Shimadzu equipment (Shimadzu corp., Kyoto, Japan) comprised of a high‐pressure pump (LC‐20AT), automatic injector (SIL‐20AC HT) with injection volume adjusted to 20 µL, detector by refractive index (RID‐10A), column furnace (CTO‐20A) maintained at a constant temperature of 35 °C (CBM‐20A), and Varian‐brand Microsorb‐MV column (pore size of 100 Å, particle size of 5 µm, filled with Amino and dimensions of 250 × 4 mm) …”